Kloster Lehnin, or just Lehnin, is a municipality in the German state of Brandenburg. It lies about 24 km west-south-west of Potsdam. The centre of the municipality is Lehnin. It is best known for Lehnin Abbey, the oldest monastery in the Margraviate of Brandenburg, established in 1180 by Margrave Otto I. The adjacent settlement developed about 1415 out …Kloster Lehnin, or just Lehnin, is a municipality in the German state of Brandenburg. It lies about 24 km west-south-west of Potsdam. The centre of the municipality is Lehnin. It is best known for Lehnin Abbey, the oldest monastery in the Margraviate of Brandenburg, established in 1180 by Margrave Otto I. The adjacent settlement developed about 1415 out of a market held by the monks outside the abbey walls.